One of the most important innovations that have come with Android 4.1.1 Jelly Bean is the ability to use the offline voice typing, until Ice Cream Sandwich instead everything could happen only if connected to the internet.
Remember that you can use the voice typing in all cases where we have the keyboard open … there just a tap on the microphone button.

Therefore, it is very simple to use the voice typing but for offline use you have to download the package in our language, here's how on Jelly Bean:

Open the system settings of the device.

Go to language and placing.

Make a tap on voice search.

Now do a tap on Download ricon. VOC. offline.

With a swype moved All tab and select Italian (Italy), will begin the download of the packageof 15 MB.

Eventually the card INSTALLED will look like this:

Now for example go to write an sms and open the keyboard, then tap on the microphone and begin to dictate the text. Of course to verify correct functioning offline just disconnect the wifi and mobile connection.
Finally, we must point out that not all keyboards will invoke Google voice dialing, operation is obviously insured with the default Android keyboard.
source : activate offline voice typing on jelly bean